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Side by Side Diff: media/base/djb2.h

Issue 1534273002: Switch to standard integer types in media/. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: more Created 5 years ago
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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef MEDIA_BASE_DJB2_H_ 5 #ifndef MEDIA_BASE_DJB2_H_
6 #define MEDIA_BASE_DJB2_H_ 6 #define MEDIA_BASE_DJB2_H_
7 7
8 #include "base/basictypes.h" 8 #include <stddef.h>
9 #include <stdint.h>
10
9 #include "media/base/media_export.h" 11 #include "media/base/media_export.h"
10 12
11 // DJB2 is a hash algorithm with excellent distribution and speed 13 // DJB2 is a hash algorithm with excellent distribution and speed
12 // on many different sets. 14 // on many different sets.
13 // It has marginally more collisions than FNV1, but makes up for it in 15 // It has marginally more collisions than FNV1, but makes up for it in
14 // performance. 16 // performance.
15 // The return value is suitable for table lookups. 17 // The return value is suitable for table lookups.
16 // For small fixed sizes (ie a pixel), it has low overhead and inlines well. 18 // For small fixed sizes (ie a pixel), it has low overhead and inlines well.
17 // For large data sets, it optimizes into assembly/simd and is appropriate 19 // For large data sets, it optimizes into assembly/simd and is appropriate
18 // for realtime applications. 20 // for realtime applications.
19 // See Also: 21 // See Also:
20 // http://www.cse.yorku.ca/~oz/hash.html 22 // http://www.cse.yorku.ca/~oz/hash.html
21 23
22 static const uint32 kDJB2HashSeed = 5381u; 24 static const uint32_t kDJB2HashSeed = 5381u;
23 25
24 // These functions perform DJB2 hash. The simplest call is DJB2Hash() to 26 // These functions perform DJB2 hash. The simplest call is DJB2Hash() to
25 // generate the DJB2 hash of the given data: 27 // generate the DJB2 hash of the given data:
26 // uint32 hash = DJB2Hash(data1, length1, kDJB2HashSeed); 28 // uint32_t hash = DJB2Hash(data1, length1, kDJB2HashSeed);
27 // 29 //
28 // You can also compute the DJB2 hash of data incrementally by making multiple 30 // You can also compute the DJB2 hash of data incrementally by making multiple
29 // calls to DJB2Hash(): 31 // calls to DJB2Hash():
30 // uint32 hash_value = kDJB2HashSeed; // Initial seed for DJB2. 32 // uint32_t hash_value = kDJB2HashSeed; // Initial seed for DJB2.
31 // for (size_t i = 0; i < copy_lines; ++i) { 33 // for (size_t i = 0; i < copy_lines; ++i) {
32 // hash_value = DJB2Hash(source, bytes_per_line, hash_value); 34 // hash_value = DJB2Hash(source, bytes_per_line, hash_value);
33 // source += source_stride; 35 // source += source_stride;
34 // } 36 // }
35 37
36 // For the given buffer of data, compute the DJB2 hash of 38 // For the given buffer of data, compute the DJB2 hash of
37 // the data. You can call this any number of times during the computation. 39 // the data. You can call this any number of times during the computation.
38 MEDIA_EXPORT uint32 DJB2Hash(const void* buf, size_t len, uint32 seed); 40 MEDIA_EXPORT uint32_t DJB2Hash(const void* buf, size_t len, uint32_t seed);
39 41
40 #endif // MEDIA_BASE_DJB2_H_ 42 #endif // MEDIA_BASE_DJB2_H_
41 43
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